Public Safety

Public Safety

What’s the Frequency…?

Building owners must know which frequency bands are being ‘beamed’ into their buildings

to ensure there is enough to serve first responders.

By Dominic Villecco

Our first article, “Know the Code,” in InBuilding magazine’s debut issue, was designed to help you, the building owner, better understand the codes that apply for the municipality where your building is located. The next important topic to discuss is which radio channels you need to employ for your inbuilding public safety radio system.

This brings to mind a favorite song, “What’s the Frequency, Kenneth?” from R.E.M.’s 1994 album “Monster.” I never paid much attention to the lyrics until I began working on this article. A well-known anchorman was attacked outside the television studio one night by a man who kept asking him, “Kenneth, what’s the frequency?”

Shortly after the incident, the attacker admitted he believed the television news stations were monitoring him and beaming messages into his head. He believed if he could find out the correct frequency, he could block the signals from entering his brain. The bizarre story is worth the read, and interesting enough that it inspired R.E.M. to write this hit song.

It’s likely you won’t have to worry about such an attacker, but as a building owner you do need to know which frequency bands are being “beamed” into your buildings because you are required to ensure there is enough to serve first responders. Knowing this information will play an important role in your upfront build/design process, and can avoid cost overruns and certificate of occupancy delays caused by significant variations in design.

Know Your Frequencies and Channels

Public safety agencies operate their two-way radio systems in a variety of FCC licensed frequency bands, as shown in this table:

Frequency Band

Common Moniker

Characteristics

Status

25-50 MHz

Low Band

-Poor inbuilding penetration

-Interference to/from common electrical devices

-Simplex operation

-Mostly phased out for public safety

138-144/148-174 MHz

VHF or High Band

-Building penetration issues but extended outdoor coverage

-Both simplex and duplex operation

-Ad hoc channel assignments

-Very congested radio spectrum; higher interference probability

-In use by many fire departments and EMS

-Heavily used in rural areas due to extended outdoor coverage and lower building density

450-470 MHz

UHF – Standard

-Very good building penetration

-Very congested radio spectrum; higher interference probability

-Consistent channel plan

-In use in many suburban and urban areas

-Also used in more populated rural areas

470-512 MHz

UHF – T Band

-Same as UHF Standard

-Being phased out by FCC by end of 2021

763-805 MHz

700 Band

-Decent building penetration

-Consistent channel plan

-Includes new FirstNet Public Safety LTE Network (less building penetration with LTE)

-New band introduced by FCC within last 10 years

-Many agencies are transitioning to this band – especially T-band operators

806-869 MHz

800 Band

-Decent building penetration

-Consistent channel plan

-In service for 20+ years

-Compatible with 700 band and here to stay

As outlined in the table, these band variations have different characteristics, including coverage, interference and shared usage. Some bands are being phased out, therefore it is important to know this when spending money to enhance your local first responder’s radio system.

Also, early two-way radio technology used simplex channels to transmit and receive voice calls. It is important to know whether your local first responder system is simplex or duplex, as simplex systems are difficult to enhance in both directions (talk-in/talk-out) and many codes require confirmation of minimum service levels in both directions. If there is more than one simplex channel to enhance – e.g., one for fire department and one for police department – it gets even more complicated, and expensive.

Typical duplex operations differ from simplex setups because they employ discrete frequencies in both directions. While this is easier to enhance using a bi-directional amplifier (BDA), VHF duplex systems with multiple channels can be extremely difficult and expensive to enhance due to the ad hoc nature of their frequency assignments. UHF systems and 700/800 systems are typically easier to enhance, and generally less expensive as a result.

Why Does This Matter To Me?

So why would a building owner need to know or understand any of this information? Our article in the previous issue discussed the role of the authority having jurisdiction (AHJ) in properly adhering to your municipality’s fire safety codes. In most scenarios, the AHJ is typically the municipal fire department. The AHJ will inform you of the frequencies used.

Some AHJs will tell you multiple bands are used by different departments. For example, our firm worked on a project that had two different VHF channels for fire and EMS, and two UHF channels for police. The client needed four BDAs just to comply with all necessary requirements for each emergency response team.

Different frequency bands need different equipment, which has a direct impact on cost. BDAs can cost anywhere between $8,000 and $20,000 depending on their complexity. And this price does not include extra costs regarding physical separation, antennas, lines, filters or installation. This project went up to six figures in order to meet AHJ requirements.

Multiple bands, as illustrated above, oftentimes mean multiple equipment configurations, which multiplies capital requirements. The real issue here is not understanding all applicable bands before designing your system and ordering equipment. Finding out you need different equipment after the fact oftentimes doubles costs. Unorganized AHJs will often ask “for the moon” just to be safe. Some will ask for as many as 16 channels. This can unnecessarily drive up costs for no valid reason.

Also, many municipalities are now transitioning to newer frequency bands released by the Federal Communications Commission (FCC). 700 MHz, for example, is a newer band. You don’t want to get caught installing an “old” system only to be told a year later you need to move to new channels. New channels means new equipment, and new equipment means new costs.

How to Protect Yourself

The difference between public safety and commercial wireless inbuilding systems is that public safety is much more discrete frequency specific. And it’s not that frequencies don’t matter for commercial wireless, but frequency pairing, and therefore planning, is a lot simpler.

Be proactive with your AHJ, and have someone who can advocate on your behalf to protect your building, your tenants and your investment. Hire a professional firm that knows the public safety frequency landscape and can help you navigate to a proper solution.

Also, make sure your professional firm knows what is going on with public safety frequency bands from a regulatory standpoint. You wouldn’t ask a bookkeeping clerk a complicated tax question, you would ask a CPA. For example, be careful if you’re requested to install in the UHF T-band, commonly referred to as just “T-band.” Anyone using this band between 470-512 MHz will lose their channels after 2021 under the Middle Class Tax Relief Act of 2012. Who would have known? Certainly anyone being asked to build one of these systems by an AHJ should know!